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How Safe Is It To Switch On A Quad Valve Amp After Being In Storage?

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Evening gents.

I have a pair of Quad II Valve amps that were in storage since January this year. After purchasing them I haven't switch them on because I'm afraid they might blow me up :facepalm:

I would ideally like to make sure they are working before I put them on the market so I would like to know, how safe is it to just plug them in and turn them on?


Put a 60 watt incandescent lamp in series with the supply

El Sid:
My first response is don't, but it depends on a few things. If you know they have been restored or at least recapped, then the few months in storage shouldn't have done any harm. But if you don't know and only have the seller's assurance that they were ok, then get someone with a variac or dim bulb tester to check them.

I've read about the bulb trick. So I just wire in the bulb on the same ac line that goes to the amps and then turn them on?

In a good scenario, both amps turn on and no smoke or issues, do I then remove the bulb and give the amps the full 220v?

A variac is not a good idea without some current limiting. The dim bulb tester is much safer method but understand what the bulb "tells" you regarding the health of the device on test. The  60W incandescent bulb may flash and go off or burn very dimly on power up. If it continues to burn brightly then something is wrong...leaky electrolytics or some other fault causing a current drain.

Make sure that there are fuses in the unit and are the correct amperage rating. (when I got the ST70, it was kitted with a 25A fuse.. glad I checked it).

If all well with the 60W bulb on startup then leave it on this for 15min or longer if you wish. Watch the bulbs response during this time. Switch off. Leave for 15min to cool. Power up again watching the bulb response. Don't start with a 100W allows more current. You could start with a 40W bulb if you have one. Once confident about the health, if good, change up to a 100W bulb for a while (if you have) before going to full power. Your nose and ears are also needed, should there be anything funny, switch off.

In the case of the Quad2, you could remove the tubes (leave the rectifier in) before doing these tests, however those experienced with these units could advise. Whether it's required to have a load across its output during this process when tubes are  in circuit is also questionable. There are follow up checks as well, watch out for red plating of anodes and listen for pops and crackles, hum and buzz coming from your test speakers. With tubes out (just the rectifier in) you could take some voltage measurements of the heater and anode supply via the sockets.


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